The Covalent Bond and Naming

1
The Covalent Bond and Naming

• Chapter 20

2
What is a Covalent Bond?
Covalent bond - bond that results from the
sharing of electrons
- occurs between nonmetallic elements
Molecule - compound formed when two or more
elements bond covalently.
3
Formation of a Covalent Bond
H
H
H
H
Single covalent bond - two electrons shared
H
H
- shown as a dash
4
Draw the electron dot structure for water, H2O
O
H
O
H
H
H
5
Double bond - sharing of two pairs of electrons
between two atoms
Triple bond - sharing of three pairs of electrons
between two atoms
6
Ionic Compounds vs. Covalent Compounds

• Ionic Compounds
• Made up of positive metallic ions and negative
  nonmetallic ions after metal transferred
  electrons to nonmetal
• Arranged in regular repeating patterns called
  crystals

7

• Form crystals where every () ion is surrounded
  by (-) ions and every (-) ion is surrounded by
  () ions
• Known as crystalline compound

8

• Have high melting and boiling points
• Conduct electricity when dissolved in
  water---electrolyte

9

• Covalent Compounds
• Made up of nonmetals sharing electrons
• Liquids, gases, or solids
• Have low melting and boiling points
• Do not conduct electricity

10
Naming Binary Molecular Compounds
Second element named with prefixes and -ide ending
First element named with prefixes (except mono)
Prefixes tell number of atoms of each element
11
Prefixes Used
mono - 1 octa - 8 di - 2 nona - 9 tri -
3 deca - 10 tetra - 4 penta - 5 hexa - 6 hepta
- 7
12
Name the compound P2O5
diphosphorus
pentoxide

• Your Turn!!
• CCl4
• PBr3
• N2S3

13
Writing Formulas from Names
Binary Molecular Compounds
- use prefixes to give subscripts for each element
What is the formula for dichlorine monoxide?
Cl2O
14
Naming Ionic Compounds
15
Binary Ionic Compounds

• Binary ionic compound compound composed of a
  metal and a nonmetal
• Oxidation number the charge on an ion
• Group 1 ? 1
• Group 2 ? 2
• Group 17 ? -1

16
Steps to naming Binary Ionic compounds

• Write the name of the first element
• Write the name of the second element with an ide
  ending
• Example CaS

Calcium Sulfide
17
Polyatomic Ions
Ammonium - NH41 sulfate - SO4-2 nitrate -
NO3-1 hydroxide - OH-1 phosphate -
PO4-3 chlorate - ClO3-1 acetate -
C2H3O2-1 carbonate - CO3-2
18
Example

• NH4NO3
• K2SO4

ammonium nitrate
potassium sulfate
19
What is the formula for the compound between
potassium and sulfate? ammonium and nitride?
K1
SO4-2
K2SO4
NH41
N-3
(NH4)3N
20
Lets Try It!!Writing Names from Formulas
1.) CaF2 calcium fluoride
2.) (NH4)3PO4 ammonium phosphate
3.) Ni(OH)2
-1
?
-1
Nickel (II) hydroxide